The present invention relates generally to the field of semiconductor devices, and more particularly to the control of electric current.
A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal.
In many cases, transistors include a source terminal, a drain terminal, and a gate terminal. The gate terminal is in contact with a region of semiconductor material, such as silicon, which is also in contact with the source terminal and drain terminal. In most configurations, the gate terminal is located between the source terminal and drain terminal. A voltage is applied to the gate terminal to control the current flow from the source terminal, through the semiconductor material, and to the drain terminal. In this case, a region of semiconductor material functions as a channel that allows the current to flow from the source terminal to the drain terminal.